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bug #40019: Some diacritics badly placed on Arabic range

Submitter:  Rosella Capriotti <rosy58>
Submitted:  Fri 13 Sep 2013 03:02:55 PM UTC
   
 
Category:  character range Severity:  3 - Normal
Item Group:  letter positioning poor Status:  Need info
Privacy:  Public Assigned to:  Stevan_White
Open/Closed:  Open Release:  * 2012-05-03
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Tue 27 Oct 2015 04:01:26 AM UTC, comment #11: 

Hi Steve,

In this page I found some diacritics as Hamza looks higher in some cases, but in bold face they looks lower.

Hsing-yen He <hammerandsickle>
Sat 14 Sep 2013 12:23:21 PM UTC, comment #10: 

Steve, the RING in U+067C is not "slightly" to the right, it's consistently placed above the next glyph, and this is clearly a glitch, I can't believe you saw such thing in another font and if you actually saw it, well it's a glitch, that's it.

Droid Naskh has the V BELOW placed exactly BELOW the REH, the same as the Unicode specimen. Again, are we seeing the same thing?

About vowel marks, you're right, I started it, but it was to make a point, that these flaws concern non-Arabic letters. See here: https://savannah.gnu.org/bugs/?40019#comment2.

Rosella Capriotti <rosy58>
Sat 14 Sep 2013 12:00:59 PM UTC, comment #9: 


> However, I wonder whether we're seeing the same thing, the
> problem is not style, it's that the ring, the dots an so on
> are really wrongly placed: take a look at what I'm seeing and
> then compare it with the Unicode sample: I'm not talking about
> STYLE, again, for instance in U+067C the ring is consistently
> misplaced to the right, while it should be placed underneath
> the letter.


Rosella, sometimes we plainly do not see the same thing.  This is not unusual.  For this reason it is so important to carefully describe what you see.

Thank you: at least for U+067C I know you mean the fact that
the ring is slightly to the right of the middle.  This was consistently done, as I had seen some other fonts with similar placement.

But I can change that, and make it more centered on the whole letter.

But depending on the style of the letter, and the slant of
the font, the meaning of center may change.  This is
borderline style.


> About the V BELOW in U+0695: I don't agree with your
> solution which is never to be found in any other Arabic
> font, other fonts consistently place it above the REH. I
> don't understand why they don't find any technical obstacle
> to that and you do.


This is strange.

You point me to the Unicode samples, saying they are right.
They have the v placed completely beneath the reh, as opposed as to the right of the bottom of the reh as it was originally in FreeSerif.

Now you send me this picture Mac(?) font, which has the v to the right of teh reh, as it before in FreeSerif.

This is quite confused.

The technical problem I mentioned is in putting any part
of the glyph below the lower limit of the font.  I can
make it happen, but only by replacing the glyph with a
reh and a positioned mark.

But that is maybe not any longer necessary..

BECAUSE, near as I can tell, now you want the mark to move back
to where it was originally.  I will do that.  But I don't
know why you had me move it in the first place.

> And I mentioned marks like U+065D because you started it :)


Oh I confess.  You caught me: I used my time machine.

Steve White <Stevan_White>
Group administrator
Sat 14 Sep 2013 11:40:59 AM UTC, comment #8: 

See image for a comparison between how Droid Arabic Nashkh and FreeSerif handle the same letter:

U+067C: RING consistently misplaced to the right in FreeSerif, correctly placed in Droid.

U+0695: V ABOVE is consistently ABOVE the REH in Droid, unlike what happens in FreeSerif.

U+06A0: THREE DOTS consistently misplaced to the right in FreeSerif, correctly placed in Droid.

U+06B2: letter in FreeSerif looks just like a normal NOON with a standard DOT ABOVE, plus THREE DOTS consistently misplaced placed to the right which inevitably collide with the next glyph. See Droid for correct glyph shape.


Rosella Capriotti <rosy58>
Sat 14 Sep 2013 11:19:56 AM UTC, comment #7: 

The samples, just like FreeSerif are Nashkh, which is used for Arabic, Persian style is Nastaliq, e very different thing.

However, I wonder whether we're seeing the same thing, the problem is not style, it's that the ring, the dots an so on are really wrongly placed: take a look at what I'm seeing and then compare it with the Unicode sample: I'm not talking about STYLE, again, for instance in U+067C the ring is consistently misplaced to the right, while it should be placed underneath the letter.

About the V BELOW in U+0695: I don't agree with your solution which is never to be found in any other Arabic font, other fonts consistently place it above the REH. I don't understand why they don't find any technical obstacle to that and you do.

And I mentioned marks like U+065D because you started it :) They'd better be discussed in the other topic, this should be reserved for letters.


Rosella Capriotti <rosy58>
Sat 14 Sep 2013 08:08:43 AM UTC, comment #6: 

OK so that wasn't it.  It escapes me why you mentioned marks such as U+065D in the same report as these other letters. I will continue to guess what you mean by the first remarks.

Overall: styles of the letters rather different.

FreeSerif is modelled after newspaper fonts -- relatively flat with horizontal baseline for dense text, whereas the style in the Unicode samples is strongly slanted, as is often used for less dense documents such as letters.  (I was also told by an Iranian that the samples are a typically Arabic fashion.)

Once again compared each letter in your list to the samples, one-by-one.  For most of them, I can only guess what evoked your emotional response.

placement of ring:
067c: up to stylistic difference, very similar.
0689: up to stylistic difference, very similar.
0693: up to stylistic difference, very similar.
06AB, B0: up to stylistic difference, very similar.

v below
0695: in smple, v is directly below reh.  in FF, it is completely to the side.  I see why: othewise the letter goes below the lower bound.  The v can be re-placed with tables wherever it needs to be, but in the main glyph it really needs to live within its vertical bounds, for technical reasons.
For now, I'll try to scrunch it under there, and keep in mind this needs further treatment.

hamza:
0678: in FF hamza is to right of base, in sample it is slightly over the base.  Maybe sample has it a bit higher too--moved accordingly.

dot above:
06AC: FF letter is styled quite differently from samples.
That given, the dot could be a bit higher.  moved it.

three dots above:
06BD: up to stylistic differences, very similar
06A0: up to stylistic differences, very similar

For the rest, we await better information.

Steve White <Stevan_White>
Group administrator
Fri 13 Sep 2013 11:11:55 PM UTC, comment #5: 

I've just downloaded the next version and I've seen no changes in the aforementioned characters, the diacritics are still badly placed.

Rosella Capriotti <rosy58>
Fri 13 Sep 2013 10:15:46 PM UTC, comment #4: 

U+061x I think they are reserved for the Koran, I can't really help you but I'll check online or ask Arabists who know those things better than I do.

However, this topic is really about precomposed characters, not diacritics. Will check tomorrow your new version and then report to you.

Rosella Capriotti <rosy58>
Fri 13 Sep 2013 10:07:11 PM UTC, comment #3: 

I think I see the source of confustion.

I thought you were referring to the form of glyphs.  But the implementation is that some of these may be glyphs; others are marks positioned with respect to glyphs.

Particularly, there is a positioned ring, but there are also precomposed letters with the ring.  Which are we referring to?

Indeed I had never understood the use of the marks in U+061x (and others), and only positioned them roughly over the preceding letter.  I have just submitted a finer positioning... in a sense... they're positioned where other diacritics are placed, which is itself only a guess.

Have a look at that, then tell me what else needs to be done.
I looked at a couple of the others, and I'm really not seeing what you mean.

The implementtion is always spotty and incomplete until somebody with better information corrects us.  We do the best we can.

It would be nice to see some text that uses these marks.
Thanks!

Steve White <Stevan_White>
Group administrator
Fri 13 Sep 2013 05:56:14 PM UTC, comment #2: 

I beg your pardon, you didn't consult the Unicode samples: http://www.unicode.org/charts/PDF/U0600.pdf because I see the correct and expected shapes in them. Just take a look.

Joining up to the JEH issue, at first glance it would look like your implementation of non-Arabic letters was patchy and incomplete, because all flaws I've been complaining about today really only concern non-Arabic diacritics/letters.

For instance: U+064F ARABIC DAMMA (Arabic diacritic) works fine but... U+065D ARABIC REVERSED DAMMA (non-Arabic) is broke... yet they should behave the same.

And don't say you're a bad guy, you're a genius :)

Rosella Capriotti <rosy58>
Fri 13 Sep 2013 05:16:03 PM UTC, comment #1: 

Rosella, I'm a bad guy.  Any placment I do is naturally bad -- it goes without saying.

All of these glyphs were made by consulting with the Unicode samples and other resources on Arabic letters. 

I was not trained in Arabic writing.  To me the glyphs still look approximately like those resources.

In order to improve the placement, we need to know in what direction the thing needs to move. 

Please in each case describe what is wrong, and how it ought to be.

Steve White <Stevan_White>
Group administrator
Fri 13 Sep 2013 03:02:55 PM UTC, original submission:  

RING badly placed on U+067C, U+0689, U+0693, U+06AB, U+06B0.
SMALL V BELOW badly placed on U+0695
HAMZA badly placed on U+0678
DOT ABOVE badly placed on U+06AC
THREE DOTS ABOVE badly placed on U+06BD, U+06A0

Rosella Capriotti <rosy58>

 

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Attached Files
file #29133:  Arabic range.png added by rosy58 (238KiB - image/png)

 

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    Follow 5 latest changes.

    Date Changed by Updated Field Previous Value => Replaced by
    2013-09-14 rosy58 Attached File- Added FreeSerif vs Droid Arabic Nashkh.png, #29135
    2013-09-14 rosy58 Attached File- Added Arabic range.png, #29133
    2013-09-13 Stevan_White Categoryoverall font problem character range
    2013-09-13 Stevan_White StatusNone Need info
        Assigned toNone Stevan_White

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